The turbines of a gas turbine engine operate at a high temperature, which can lead to a short lifetime of the components. Cooling air is used to reduce the temperature of these components during operation of the turbine. The cooling air is provided indirectly by air used for sealing purposes and/or low pressure feed purposes. The effectiveness of this cooling is not very high and, in engines where the cycle and operating conditions lead to particularly high temperatures, the turbine disc ring can overheat.